EUROPE – Researchers from Spain and France have used a new type of technology to more accurately detect traces of peanut in foods, in a study published in the Journal of Near Infrared Spectroscopy.
If foods are processed in common facilities, it can be impossible to prevent contamination with traces of peanut, leading to the vague warning “May contain peanuts” on many food labels.
Even at trace levels, this contamination can be a major problem for individuals who are allergic to peanuts, potentially triggering a life-threatening reaction.
However, these warnings of peanut contamination could soon lose much of their uncertainty, thanks to a novel form of near infrared (NIR) spectroscopy known as NIR hyperspectral imaging (HSI).
This analytical technique detects specific molecules based on their absorption and reflection of light at near infrared wavelengths.
Scientists have already shown that peanut powder generates different NIR spectra to various other powdered foodstuffs, including wheat flour, milk and cocoa, allowing any contamination to be detected.
The problem with conventional NIR spectroscopy is that it collects an average NIR spectrum over a large area, meaning that trace peanut contamination may be missed. The scientists decided to try to solve this problem using NIR HSI, which produces images in which every pixel contains spectral data.
Each pixel can thus contain information about peanut contamination, making NIR HSI much more sensitive than conventional NIR spectroscopy and allowing it to detect trace levels of peanut over a large area.
They developed a scoring system that could determine whether or not specific pixels in an image of wheat flour contained peanut powder from their NIR spectra.
Using this scoring system, they could then estimate the level of contamination by simply determining the percentage of pixels that contained peanut powder.
They tested this system on samples of wheat flour spiked with powder from four different types of peanut, including raw, blanched and roasted, at concentrations varying between 0.01 per cent and 10 per cent .
The system was able to detect peanut contamination even at 0.01 per cent , although it could only accurately determine the level of contamination at between 0.1 per cent and 10 per cent .
“These results show the feasibility of using HSI systems for detecting traces of peanut and similar products that are present in low percentages in powder foods with contrasting spectra,” said lead researcher Puneet Mishra.
Mr Mishra and his colleagues are now looking to apply the same technique to detecting contamination by other nuts, which can also cause serious allergic reactions.
“Although peanut is the most common cause of nut allergy, peanut allergic patients are frequently also sensitive to tree nuts,” he explained.
“We are presently sampling different tree nut mixtures of almond, walnut and hazelnut to check the feasibility of HSI for detecting them.”
TheCropSite News Desk
